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Thanks @TimW it is basic, I thought you have a more elaborate model. RR for example is not completely constant and has a (small) velocity related component. Some consumption goes to overcome internal resistance (speed reducer, bearings etc.)
But I agree that the basic equations with the basic assumptions will be close enough most of times.
 

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But I agree that the basic equations with the basic assumptions will be close enough most of times.
Am I right in thinking that the most significant figures missing from the calculation is the efficiency of motors and drive train in converting 1kWh of electricity from the battery into the energy needed through the wheels?
Can we expect that all Kia and Hyundai models on the same platform with rear wheel drive would have similar drive train efficiencies? And would this efficiency vary with speed?
If we modelled a similar body, weight and tyres on the VW platform compared with the Hyundai platform, which would be more efficient?
And if the Hyundai i800 van was built on the E-GMP platform, what Wh/km would be predicted?
 

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Am I right in thinking that the most significant figures missing from the calculation is the efficiency of motors and drive train in converting 1kWh of electricity from the battery into the energy needed through the wheels?
Yes, that's definitely missing. I wonder how much that is a constant, and how much is a function of other factors (speed, torque, power, etc.).
 

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So, just to share, this is my performance model of the Ioniq 5 AWD 72.

First the inputs and a few summary results:
Slope Line Font Screenshot Technology

Motor intertia and transmission efficiency are best-guess.
The rolling resistance formula has a tire pressure component and a speed component, but it is still more or less generic and also best-guess.
Aerodynamic CdA are based on what I have found in this forum and may be off a bit.
With the above values, the 0-100 time (5.3 sec) and the consumption at 100kph (174 wh/km) seem reasonable.
Weight distribution, CG height, Wheelbase and Tire grip are used in the model to check for traction limited scenarios. It seems like the front motor was sized optimally. See below.

This plot shows the raw output of the motors as a function of speed, based on published specs.
Slope Rectangle Font Parallel Terrestrial plant


This plot shows the propulsive force at the front and rear axles.
The dotted lines are the available traction at each axle, based on the Tire grip parameter and taking into account weight transfer during acceleration.
The blue line is the lesser of the front and rear "traction margin". It shows that the front wheels should not be traction limited on a dry surface. But they're close, so up to about 35 kph, a bump or paint on the road will probably result in wheel spin and ESC kicking in. Maybe someone out there that already has their car can confirm this.
Colorfulness Slope Rectangle Font Parallel


This is the drag race plot, showing acceleration, speed and distance traveled as a function of time.
Slope Rectangle Font Parallel Pattern


And finally, the drag curves.
For those interested in consumption as a function of speed, it looks just like the green curve (total drag). Just divide the right axis values by 3.6 to get wh/km.
Human body Slope Rectangle Font Parallel


Again, don't bet your pink-slip on what you see here. The math is sound, I think, but some of the input values are estimates.
 

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So, just to share, this is my performance model of the Ioniq 5 AWD 72.
Thanks a lot.
UK specs say rear motor max. power is 160kW (you wrote 155) and only 64kW front for a total of 224kW.
Can you run the model also for the Ioniq 5 RWD 72.6 and share the results? Will appreciate.
 

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I have the same request, please, for the RWD, 72.6. Also, would you be willing to share the spreadsheet ?

Thanks
CJ
 

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Are you guys accounting for weather effects in your models? In Bjorn's test it was raining much/most of the time (It's always hard to tell exactly how badly). I don't know if that could produce the discrepancy (because I can't be bothered to work out the math!)
 

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Are you guys accounting for weather effects in your models? In Bjorn's test it was raining much/most of the time (It's always hard to tell exactly how badly). I don't know if that could produce the discrepancy (because I can't be bothered to work out the math!)
I think this spreadsheet/model cannot take into account degradation due to 'unknowable' weather patterns. How could it ?
The best we can hope for, is that it gives figures on some nominal values under 'good/perfect' conditions, where we must then further account for a 10/20/30% ? reduction based on potential bad weather.

Other factors that can affect it all, is also the wheel size/ aero cap effects. The 20" in the initial P45/FE deliveries are aero capped by default, but from the 19" there are already multiple variants which have the aero cap, and non aero cap. On Tesla forums, there are indications that their aero caps on the same wheels can provide a 5-6% difference in range alone !!
 

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1) The models assumes a dry, asphalt road. Tire grip is coefficient is 0.9, which is probably a bit conservative given the braking distances I found (100-0 in 34m = 1.1g).
2) I increased the Cd to 0.3 (from 0.288) and the consumption at 90 and 120kph are pretty close to Bjorn's range test. Aero and rolling resistance are definitely opportunities to tweak the model, if I had more real-world consumption numbers.
3) I added a table to capture the weight and available power the various battery and drive configurations.
The power numbers are from the Ioniq 5 official brochure.
Product Rectangle Font Parallel Electric blue


Weight took a little more digging. I came to the conclusion that the front motor adds 110kg, the 72 kwh battery adds 80kg, and the 77 kwh battery adds another 25kg. I also added a field for "Option weight" for bigger wheels, fancy seats, sub-woofers, etc... I just guessed 80kg for that. Less premium trims may be a bit lighter. I also added an 80kg driver.

4) The 72 RWD model results look like this:
Font Slope Biome Line Screenshot


Colorfulness Rectangle Slope Font Parallel


To share the the spreadsheet, I will need to figure out how to share a copy of a google sheets file (as opposed to a collaborative copy). Exporting to Excel didn't work very well.
 

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Thank again @PharAstro
Bjorn's range test was done on wet road plus rain at least part of the test, as far as I remember. So increasing Cd to match his consumptions makes it a bit of unjust to the car?
Anyways, thanks. If you can find a way to share, we will be able to tweak the model ourselves...
 

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Thank again @PharAstro
Bjorn's range test was done on wet road plus rain at least part of the test, as far as I remember. So increasing Cd to match his consumptions makes it a bit of unjust to the car?
Anyways, thanks. If you can find a way to share, we will be able to tweak the model ourselves...
my exact same sentiments.
great work PharAstro.
Trust in your own math/data for your modeling, and do not be tempted to adjust to external singular data points because then you may fall into a trap of making your model becoming biased.
I would also keep the Cd at 0.288. There is no reason to doubt those numbers when it is gained in so controlled an environment.

Interesting to see the consumption difference being so little between the awd and rwd actually. At higher speed, the difference becomes moot, but at lower speed, it is still only a few percent.
 

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This is what I found on sharing a google spreadsheet. I hope this helps. After you do this you should have a link you can put in this forum.
Head to the Google Sheets website, open the file you want to share, and then click File > Publish to the Web. If you don't want to share the entire document, you can choose a single sheet to publish online. To do this, click “Entire Document,” and then select the sheet from the drop-down menu. Click “Publish.”
 

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I think this spreadsheet/model cannot take into account degradation due to 'unknowable' weather patterns. How could it ?
The best we can hope for, is that it gives figures on some nominal values under 'good/perfect' conditions, where we must then further account for a 10/20/30% ? reduction based on potential bad weather.

Other factors that can affect it all, is also the wheel size/ aero cap effects. The 20" in the initial P45/FE deliveries are aero capped by default, but from the 19" there are already multiple variants which have the aero cap, and non aero cap. On Tesla forums, there are indications that their aero caps on the same wheels can provide a 5-6% difference in range alone !!
I'm unfamiliar with aero caps, but The 19" wheels themselves are supposed to provide a few $ better efficiency. Are there different variants of the 19" wheels?
 

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Other factors that can affect it all, is also the wheel size/ aero cap effects. The 20" in the initial P45/FE deliveries are aero capped by default, but from the 19" there are already multiple variants which have the aero cap, and non aero cap.
The other substantial difference between the wheel sizes is that Hyundai made the deliberate decision that the 20" wheels should have more performance-oriented tyres. There was an interview with senior engineers where they discussed the differences - from memory the 20" tyres had a 15% greater rolling resistance.

Interesting to see the consumption difference being so little between the awd and rwd actually.
That's not too big a surprise - only around a 5% difference in mass and therefore rolling resistance, so maybe 1-2% difference in consumption at highway speeds. I suspect the difference in WLTP range is because the test cycle includes much more changes in speed than constant highway driving, so the front motor is engaged much more for acceleration.
 

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I tried to "publish" the spreadsheet. The resulting link works, but is read-only, which is not what we want. So I'm still stuck on that front.

Regarding AWD vs RWD efficiency - my model currently does not consider the losses associated with the front differential and/or gearbox spinning. The "transmission efficiency" only scales net thrust for the acceleration calculations, and the consumption due to rolling and aero drag at a given speed. The small difference in consumption between RWD and AWD is due to the weight, which is a factor in rolling resistance. That difference vanishes at high speeds because aero drag dominates. Hmm... I could add a "transmission drag" which I think in real life is something like T = A + B*rpm. But I have no idea what A and B would be. I haven't yet found any good references online for that particular aspect of vehicle drag.

But I do have a thought. Anyone that has had the opportunity/desire to spin a car wheel when the car is lifted up might be able to relate. If you manually spin one driven wheel and the axle has an open differential, the effort to spin that wheel (and the opposite one in reverse) is analogous to the Ioniq 5 front axle when the motor is disengaged. I haven't done this in a while, but to my recollection, it's not very hard, at least at slow speed. Before doing any math, I guess 20N (2kg) as the force to apply tangentially on the tire to spin it. Then I checked the model and saw that the total drag at 100kph is 600N. Adding 20N due the spinning front differential would represent a 3.3% increase. The weight of the AWD adds 13N of rolling resistance at 100kph, or another 2.2%. The total is 5.5%, which maybe a little higher than the overall range difference between the two models. Maybe my 20N guess was a little high.

So I went ahead and added a "Front axle drag" parameter to model. It does not affect the acceleration curves because the assumption there is that the front motor is engaged, meaning that the differential bevel gears are not spinning and only transmission losses apply. Front Axle Drag is just added to the total drag at all speeds, for purposes of calculating consumption.

This table shows the relative consumption of RWD and AWD with this new parameter implemented and set to 10N. I did change Cd back to 0.288 as suggested in previous replies.

Line Font Number Electric blue Composite material
 

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I tried to "publish" the spreadsheet. The resulting link works, but is read-only, which is not what we want. So I'm still stuck on that front.
If you publish the google spreadsheet and provide the link, anyone can download the spreadsheet. This is read only, but anyone can open this spreadsheet as an editable copy and then edit the spreadsheet as they wish. You don't need to change anything.
 

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It's pretty easy, the faster you go the less sense it makes to choose the Ioniq 5. If you commute at a very low average the Ioniq 5 would be a great choice looking at efficiency. At higher speeds it simply sucks. Hopefully Ioniq 6 and orhet coming sleeker cars will make high speed travel possible too. Possibly KIA will make something on the same platform too besides the EV6. Low speed tests makes me think it got a good enough drive train, it's just the big boxy body that kills it.
 

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There isn't much room in the basic physics to get a better performance from a large and heavy car and have the space inside and travel at speed. The EV6 gets marginal improvement in range by having less frontal area, but less room inside.
Where there is room to improve is in the overall weight of the vehicle - and that largely from new battery technologies that are much lighter per kWh. But they may not come on stream for several years.
There is still room for improvements in the efficiency of energy conversions from battery to movement, and here the use of heat pumps for battery management to keep the battery at optimum temperature offers the biggest gains. Improvements in the efficiency of electric motors to movement is likely to be small. Tyres have a trade off between efficiency and grip.
Travelling more slowly and keeping a constant speed is the best solution for getting a longer range.
I have Kia E-Soul at the moment and most of my regular travelling is within its range, and charging over night at home. I should get exactly the same range or better from the Ioniq 5. For 90% of the population that is more than enough, and being able to recharge quickly on those very few longer journeys means I would never have to worry about running out of charge. Just plan for a 20 minute break every couple of hours - which I would do anyway.
The Ioniq 5 hits a sweet spot of internal space and range, ease of driving and comfort + all wheel drive + the ability to use the large battery as an emergency power supply.
 

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If you publish the google spreadsheet and provide the link, anyone can download the spreadsheet. This is read only, but anyone can open this spreadsheet as an editable copy and then edit the spreadsheet as they wish. You don't need to change anything.
Publish doesn't work. You just get a static webpage. Conversions to XLSX screws up the graphs. But Google Docs link sharing works.

Click here to make a copy of Car Power PharAstro. Your browser needs to be logged into your Google account.
 
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